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1.
The time has come to proceed from forms of givenness of the word to forms of the word as such. They can, if you like, be called external and inner structures. Humboldt, however, preferred to speak of the external and inner forms of the language. Shpet adopted precisely this distinction. Why did this problem interest Shpet? Already in [Appearance and sense], he had set the task of returning to the source of pretheoretical, living science. Shpet wrote that the outer cover of words and logical expressions obscure the objectified meaning and that it was necessary to remove another cover from the objectified sign so as to grasp a certain genuine intimacy, and in it the fullness of being (Shpet, 1914. Pp. 5-6). We shall keep in mind this major undertaking posed by this scientist. The existence of the inner form of words should not come as a surprise. That same year (1914) Ortega y Gasset wrote that material objects have a third dimension. However, we cannot see or touch it: "For just as depth needs a surface beneath which to be concealed, the surface, or outer cover, in order to be so, needs something over which to spread, covering it" (Ortega y Gasset, 2000. Pp. 62-63).  相似文献   

2.
Summary The choriocapillaris is a fenestrated capillary bed located posterior to the retinal pigment epithelium. It serves as the main source of supply to the photoreceptors, retinal pigment epithelium, and other cells of the outer retina. The permeability of these capillaries to intravenously injected ferritin (MW — approx. 480,000; mol. diam. 11 nm) was examined in the mouse, rabbit, and guinea pig, each of which is characterized by a different type of retinal vascularization. In all three species, the bulk of the ferritin remained in the capillary lumina, where it appeared to be blocked at the level of the diaphragmed fenestrae. Some ferritin was present in endothelial cell vacuoles. The results confirm previous work on the rat choriocapillaris and indicate that the barrier function of the choriocapillary endothelium is present even among species in which the retinal circulation differs significantly.Supported by NIH grant EY03418  相似文献   

3.
Chosen at random 38 diastolic preparations of human hearts from persons having not any cardiac pathology, as demonstrate the postmortem examination, have been investigated. The left ventricle casts have been made during the first 24 hours after death according to a strictly fixed technique by means of filling the cardiac chambers with polymere mass--protacryl--under a physiological pressure of the diastolic filling. The trabecules are arranged as a spiral from the apex of the ventricle up to the atrioventricular fibrous ring, with approaching the apex the spiral step increases and the trabecules straighten. The left ventricle cast is devided into some planes, the envelopes and the trabecularity lines are measured. Average values of the shift in the trabecularity lines I, II, III and in the cross sections B, C, D, E are defined in relation to the plane A and in every case in relation to the previous plane Cn-1. The data obtained are presented in tables and diagrams. The greatest shift demonstrate the trabecularity lines I running predominantly along the posterior wall of the left ventricle in the planes B and which are situated nearer to the atrioventricular ring projection. Owing to the presence of the spiral-shaped course of the trabecules, it is possible to suppose that it influences the blood stream twisting clockwise in the left ventricle during the diastole phase. This indicates the necessity to work out some new constructions of artificial cardiac valves, securing the twisted blood stream. The condition mentioned should be taken into consideration while making prostheses of the cardiac valves.  相似文献   

4.
Summary The differentiation of the spermatid, especially in reference to the formation of the flagellum, and transformation of the shape of the nucleus was investigated in the domestic fowl.In the early stage of the spermatid, a prominent Golgi apparatus appears around the centrioles. The Golgi vesicles then surround the axial-filament complex which develops from the distal centriole. These vesicles fuse to form continuous membrane at the earliest stage of flagellar formation, and in the succeeding stage Golgi lamellae are attached to the plasma membrane of the developing flagellum. From these observations, it is assumed that Golgi apparatus may be a source of the membrane system of the flagellum.The microtubules distributed around the nucleus form the circular manchette. The anterior region of the nucleus with the manchette is cylindrical in shape and the posterior region without it remains irregular in shape. When the circular manchette has been completed, the whole nucleus acquires a slender cylindrical shape. The circular manchette then changes into the longitudinal manchette. The nuclei of spermatids without a longitudinal manchette are abnormal in shape. In view of these observations it is assumed that the nuclear shaping of the spermatid may be accomplished by circular manchette and the maintenance of shape of the elongated nucleus by longitudinal manchette.The authors wish to thank Mr. Takayuki Mori for his helpful suggestions and technical advices  相似文献   

5.
日光温室采光面三效率计算模式及其优化选择研究   总被引:7,自引:0,他引:7  
本文针对日光温室常见的3种采光面(圆弧面、椭圆和抛物面),给出了各自采光效率、土地使用率和保温效率(简称三效率)的理论计算模式,并通过分析得出,各个高效采光面上的采光效率均随纬度增加而降低,随距冬至的日数而增加,随作物高度而降低,随高跨比增加而增加。在三种采光面中,无论时间、地点、高跨比和种植高度怎样变化,均以圆弧面的采光效率为最高,椭圆面次之,抛物面最低。另一方面,从土地使用效率来看,椭圆面最高,但它的保温效率最低。因此,采光面形状的选择应因使用对象而宜,本文给出了最佳选择建议。  相似文献   

6.
Patients with calcaneus fractures experience considerable interferences with daily living activities. The quality of anatomical reconstruction is important because of its influence on functional outcome. The aim of this study was to develop an automatic algorithm based on computer tomographic (CT) images to quantify the integrity of calcaneal joint surfaces. Validation of this algorithm was done by assessing intra-individual variations of characteristic joint parameters. Bilateral hind foot CT data of 12 subjects were manually segmented, and 3D models from the calcaneus, talus and cuboid were generated. These models were implemented in a custom-made software to analyse the area, 3D orientations and bone distance of the joint surfaces of the calcaneus. Three joints were detected, and the calculated parameters were compared between right and left hind foot by the evaluation of the directional asymmetry (%DA). The results were statistically analysed with a paired t-test. The median of area (5–7 %DA) of the joint surfaces and the distance between two articulating surfaces (8–9 %DA) showed the greatest intra-individual differences. Median differences in 3D orientation were comparatively low (1–2 %DA). None of these differences was statistically significant. Inter-individual variations among subjects were several magnitudes larger than intra-individual differences. The presented computational tool provides 3D joint-specific parameters of the calcaneus, which enable to describe their respective joint integrity. The results show that only small intra-individual differences within the anatomy exist. Surgical treatment should take place with the aid of CT data from the contralateral side. Thus, a good restoration of the anatomy may be reached. The computational tool assesses the quality of reduction, and may be helpful to evaluate the outcome and quality of operative treatment based on the calculated joint-specific parameters of joint reconstructions in the hind foot.  相似文献   

7.
Summary By the use of scanningand transmission electron microscopy, the possible sources of errors in interpretation of the microcirculation of the pancreas can be reduced in comparison to the classical India-ink injection method. Sphincter-like structures in the capillary wall of the cat pancreas are established by pericytes. These sphincters encircle the junctional zones between the endocrine and exocrine capillaries. They are assumed to be regulatory structures of blood flow and to regulate indirectly hormone secretion according to demand.This work was financially supported through the kindness of Eli Lilly GmbH, Bad Homburg, Bundesrepublik Deutschland  相似文献   

8.
In local application of substances with a mediator action (adrenaline, acetylcholine, histamine) and blockers of specific receptors (dihydroergotoxin, inderal, atropine and of subcutaneous dimedrol) together with dicaine it was possible to reveal a distinct presence in the cornea of the eye of the mediator receptors capable of influencing one another. Pharmacological analysis permitted a supposition to be made that there were two receptor systems in the sensory nerve endings of the cornea; these systems were in reciprocal inhibitory relations; due to this their regular influence on the processes of excitation and inhibition is effected in the sensory nerve ending.  相似文献   

9.
We present an overview of the results obtained in a cross-transplantation system using respectively controls,jimpy (jp), andshiverer mutant mice as donors and recipients. Homochronic transplantations (O days into O days) demonstrated that jp environment is non-toxic for non-jp cells and that, contrary to in vitro, jp oligodendrocytes phenotype cannot be modified by environmental factors at this age. Transplantations of embryonic fragments into the newborn brain demonstrated that in contrast to oligodendrocyte precursors contained in fragments of newborn tissue, jimpy embryonic stem cells are sensitive to environmental factors able to modulate the proportion of surviving oligodendrocytes. In addition, these series evidenced a disjunction between the surviving and the myelinating capacity of jp cells demonstrating a pleiotropic effect of the jp mutation on oligodendrocyte biology. Results are discussed with regards to the recent molecular biological finding on the role of the DM20/PLP gene.Special issue dedicated to Dr. Majorie B. Lees  相似文献   

10.
Guanidinobenzoatase (GB), a proteolytic enzyme found in the epididymal fluids of mice, was purified to apparent homogeneity by molecular sieving and affinity chromatography. It has a molecular mass of 71 kDa and its enzymatic activity is heat labile and sensitive to EGTA. Its kinetic parameters (Km of 6.66 μM and a Vmax of 4.38 nmol/min/mg) were determined using 4-methylumbelliferyl-p-guanidinobenzoate (MUGB) as the substrate. GB activity is concentrated in the cauda epididymal region of the genital tract. Heat-solubilized whole zonae, biologically active ZP3, and several serine proteinase inhibitors, including a proteinase inhibitor endogenous to the male genital tract, effectively block the ability of GB to hydrolyze MUGB. Pretreating cumulus-free, zonae intact oocytes with purified GB reduces, in a concentration-dependent manner, the number of sperm able to bind to the zonae. The function of the soluble enzyme is not known. Its ability to bind both trypsin inhibitors and ZP3 suggests a possible role in gamete recognition. Mol. Reprod. Dev. 47:204–209, 1997. © 1997 Wiley-Liss, Inc.  相似文献   

11.
This study proposes to estimate the horizontal positions of the body's centre of gravity (CoG) in a standing posture, on the basis of the horizontal positions of the centre of pressure (CoP). The latter were measured with a force plate, and using a low-pass filter defined by a mathematical relationship of the relative magnitude of the CoG with respect to the magnitude of the CoP, as a function of the frequency oscillations (Brenière, 1996, Journal of Motor Behaviour 28, 291–298). This relationship was computed from the angular momentum equation applied to the whole body with respect to the CoG using the inverse dynamics approach and force plate recordings, and considering the CoP and CoG oscillations as simple periodic functions. Five subjects were asked to perform voluntary oscillations along medio-lateral and antero-posterior axes, keeping their bodies straight, and without moving their feet. The CoG accelerations measured by the force plate were compared with the CoG accelerations derived from the estimated CoG positions. The average root-mean-square difference between these accelerations was very small, confirming the accuracy of this method. This simplified way to calculate the CoG positions, rarely measured in standing, allows a comparative assessment of motion performance. This method could also be applied to other kinds of movement such as walking.  相似文献   

12.
K. Hausmann 《Protoplasma》1979,100(2):199-213
Summary The membranes of the pellicle of the ciliatePseudomicrothorax dubius are investigated using thin section electron microscopy and freeze-fracture replicas. The plasma membrane is covered by a surface coat and is connected to the outer alveolar membrane by short, sometimes branched, bridges. The inner alveolar membrane is coated on both sides. The epiplasm lies in intimate contact with the cytoplasmic surface of this membrane, and there is a corresponding deposit on the other surface. This deposit is regularly striated.The epiplasmic layer and the alveoli are interrupted at sites of cytotic activity,e.g., the attachment sites of trichocysts, the cytoproct, and the parasomal sacs. The striated deposit ends where the epiplasm ends, indicating a direct relationship between these two epimembranous layers.There is a deposit along the sides of the first part of the tip of the trichocysts, and in this region the trichocyst membrane is free of intramembranous particles.The membrane of the parasomal sacs has a coat on both surfaces. That on the extraplasmic surface is similar to the surface coat of the plasma membrane. The origin of the cytoplasmic coat is unknown. The cytotic activity of these sacs is indicated by their highly irregular profiles.  相似文献   

13.
A synopsis of the biology of the Ascomycotina. A wide variety of classifications of the Ascomycotina has been proposed but a consensus is being reached on the main orders that it is appropriate to recognize. Most of these orders are well characterized with respect to their ecology and nutritional requirements although defined primarily on morphology. The 43 orders are displayed diagrammatically to illustrate their host and substratum requirements. This display is intended to stimulate argument and research by broadening the consideration of evolutionary pathways to include ecological and nutritional factors. It will also be of value as a teaching aid; overlays can be constructed to show additional features not treated here.  相似文献   

14.
On the analysis of competition at the level of the individual plant   总被引:6,自引:0,他引:6  
Summary The extent to which some measure of local crowding can account for the performance of individual plants is examined with reference to populations of two species of annual plant. Only a relatively small proportion of the variation in individual plant yield could be accounted for by measures of local crowding. These included the number of close neighbours, an estimate of the area available to each plant and competitive pressure. A multiple regression that took account of both emergence time and local crowding increased the proportion of variance that could be accounted for up to 50%. Computer simulations of the growth of indivudual plants in monoculture were then caried out in order to determine whether the unexplained variation resulted from fundamental flaws in the models or from unaccounted for sources of variation in the field. The results from the simulations again indicated that only a relatively low proportion of the variation in individual plant yield could be accounted for by emergence time and local density, even though these were known to be the only variables present. These findings are discussed in relation to the relative importance of one-sided and two-sided competition, and the complex cross-correlations that occur between individuals in plant populations. These two factors will make it very difficult for field workers to determine accurately what factors determine individual plant yield and in particular to predict the effects of local crowding on the performance of individual plants.  相似文献   

15.
A computer program was used to test Wong's coevolution theory of the genetic code. The codon correlations between the codons of biosynthetically related amino acids in the universal genetic code and in randomly generated genetic codes were compared. It was determined that many codon correlations are also present within random genetic codes and that among the random codes there are always several which have many more correlations than that found in the universal code. Although the number of correlations depends on the choice of biosynthetically related amino acids, the probability of choosing a random genetic code with the same or greater number of codon correlations as the universal genetic code was found to vary from 0.1% to 34% (with respect to a fairly complete listing of related amino acids). Thus, Wong's theory that the genetic code arose by coevolution with the biosynthetic pathways of amino acids, based on codon correlations between biosynthetically related amino acids, is statistical in nature. Received: 8 August 1996 / Accepted: 26 December 1996  相似文献   

16.
Summary Neural lobes from rats subjected to neurohypophysial hormone-releasing stimuli were examined electron microscopically following fixation in 4 % tannic acid in 2.5 % glutaraldehyde. This fixation allowed the delineation of the perivascular space in the neural lobe tissue. Measurement of the area of the perivascular space showed that it was significantly increased in the rats subjected to vagal stimulation and intraarterial calcium ions compared to the control rats. The rats which had been subjected to haemorrhage as a hormonereleasing stimulus did not show any significant change in the area of the perivascular space. The significance of these findings in relation to hormone release is discussed.  相似文献   

17.
Electrical treatment of resin-coated voltammetric carbon fibre electrodes with triangular voltage at low (1.1) pH resulted in electrodes almost insensitive to ascorbic acid (AA) and dihydroxyphenylacetic acid (DOPAC) while their response to 5-hydroxyindoleacetic acid (5-HIAA) was practically the same as after treatment in the usually employed pH 7.4 medium. Electrodes treated at high pH (12.0), on the other hand, were more sensitive to AA and DOPAC than those treated at pH 7.4 and less sensitive to 5-HIAA. Exposing resin-coated electrodes to the treatment media without electrical treatment was not sufficient to obtain the same results as with the application of the current. Electrodes without resin coating were sensitive to AA without electrical treatment while coated electrodes were not. Electrical treatment increased the sensitivity of non-coated electrodes and rendered coated electrodes even more sensitive than non-coated ones. Treatment of coated electrodes for a maximum sensitivity to 5-HIAA was found to require less time than to obtain maximum sensitivity to the other compounds. Present results suggest that it is possible to prepare selective voltammetric electrodes by choosing the right parameters for their electrical pretreatment.  相似文献   

18.
The unambiguous assignment of the nuclear magnetic resonance (NMR) signals of the alpha-substituents of the haems in the tetrahaem cytochrome isolated from Shewanella frigidimarina NCIMB400, was made using a combination of homonuclear and heteronuclear experiments. The paramagnetic (13)C shifts of the nuclei directly bound to the porphyrin of each haem group were analysed in the framework of a model for the haem electronic structure. The analysis yields g-tensors for each haem, which allowed the assignment of some electron paramagnetic resonance (EPR) signals to specific haems, and the orientation of the magnetic axes relative to each haem to be established. The orientation of the axial ligands of the haems was determined semi-empirically from the NMR data, and the structural results were compared with those of the homologous tetrahaem cytochrome from Shewanella oneidensis MR-1 showing significant similarities between the two proteins.  相似文献   

19.
The effect of the cerebral 5-hydroxytryptamine system on the turnover of striatal 3,4-dihydroxyphenyl-ethylamine (dopamine) was investigated by measuring the level of dopamine and one of its metabolites in rats depleted of cerebral 5-hydroxytryptamine or treated with a 5-hydroxytryptamine receptor blocker. Treatment with p-chlorophenylalanine induced, in addition to a reduction in striatal 5-hydroxytryptamine and 5-hydroxyindol-3-ylacetic acid, an increase in the striatal concentration of dopamine, a diminution in the concentration of homovanillic acid in the same cerebral area, and a reduction in the rise of this acid after the administration of a butyrophenone derivative or tetrabenazine. Treatment with methysergide also reduced the increase of homovanillic acid induced by the butyrophenone. When probenecid was given to rats treated with p-chlorophenylalanine, homovanillic acid failed to accumulate, whereas the accumulation of 5-hydroxyindol-3-ylacetic acid was unaffected. The decay of dopamine after alpha-methyl-p-tyrosine administration was normal for the first 6 h but was later reduced in rats given p-chlorophenylalanine or methysergide. The results suggest that the lack of activation of 5-hydroxytryptamine receptors leads to a reduction in the turnover of dopamine in the nigrostriatal pathway.  相似文献   

20.
Burykin A  Kato M  Warshel A 《Proteins》2003,52(3):412-426
The availability of structural information about biological ion channels provides an opportunity to gain a detailed understanding of the control of ion selectivity by biological systems. However, accomplishing this task by computer simulation approaches is very challenging. First, although the activation barriers for ion transport can be evaluated by microscopic simulations, it is hard to obtain accurate results by such approaches. Second, the selectivity is related to the actual ion current and not directly to the individual activation barriers. Thus, it is essential to simulate the ion currents and this cannot be accomplished at present by microscopic MD approaches. In order to address this challenge, we developed and refined an approach capable of evaluating ion current while still reflecting the realistic features of the given channel. Our method involves generation of semimacroscopic free energy surfaces for the channel/ions system and Brownian dynamics (BD) simulations of the corresponding ion current. In contrast to most alternative macroscopic models, our approach is able to reproduce the difference between the free energy surfaces of different ions and thus to address the selectivity problem. Our method is used in a study of the selectivity of the KcsA channel toward the K+ and Na+ ions. The BD simulations with the calculated free energy profiles produce an appreciable selectivity. To the best of our knowledge, this is the first time that the trend in the selectivity in the ion current is produced by a computer simulation approach. Nevertheless, the calculated selectivity is still smaller than its experimental estimate. Recognizing that the calculated profiles are not perfect, we examine how changes in these profiles can account for the observed selectivity. It is found that the origin of the selectivity is more complex than generally assumed. The observed selectivity can be reproduced by increasing the barrier at the exit and the entrance of the selectivity filter, but the necessary changes in the barrier approach the limit of the error in the PDLD/S-LRA calculations. Other options that can increase the selectivity are also considered, including the difference between the Na+...Na+ and K+...K+ interaction. However, this interesting effect does not appear to lead to a major difference in selectivity since the Na+ ions at the limit of strong interaction tend to move in a less concerted way than the K+ ions. Changes in the relative binding energies at the different binding sites are also not so effective in changing the selectivity. Finally, it is pointed out that using the calculated profiles as a starting point and forcing the model to satisfy different experimentally based constraints, should eventually provide more detailed understanding of the different complex factors involved in ion selectivity of biological channels.  相似文献   

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